Background

Question 1

What is the incidence of anal cancer in the United States?

Answer 1

∼7,000 cases/yr in the United States.

Question 2

Is there a sex predilection for anal cancer?

Answer 2

Yes. Anal cancer is more common in females than males (2:1).

Question 3

What are some risk factors for anal cancer?

Answer 3

Hx of STDs/anal warts; multiple sexual partners (>10); anal-receptive intercourse; immunodeficiency (HIV, solid organ transplantation); smoking; Hx of Cx, vulvar, or vaginal cancer (HPV related malignancies).

Question 4

Is anal cancer an AIDS-defining illness?

Answer 4

No. However, the demographically adjusted rate ratio for HIV-infected men and women relative to uninfected cohorts is 80 and 30, respectively. Cx cancer is an AIDS-defining illness.

Question 5

What is the predominant histology of anal cancer?

Answer 5

SCC (75%–80%) is the predominant histology.

Question 6

What virus strains are strongly associated (assoc) with anal cancer?

Answer 6

HPV strains 16, 18, 31, 33, and 35 are strongly assoc with anal cancer. Anal cancers are assoc. with HPV infection in 75%–90% of cases, with HPV16 the most common subtype.

Question 7

How long is the anal canal, and where does it extend?

Answer 7

The anal canal is 4-cm long, extending distally from the anal verge (palpable junction b/t the internal sphincter and SQ part of the external sphincter, aka the intersphincteric groove) to the anorectal ring (where the rectum enters the puborectalis sling) proximally.

Question 8

What is the histopathologic significance of the dentate line (aka pectinate line)?

Answer 8

The dentate line is the anatomic site where mucosa changes from nonkeratinized squamous epithelium distally to colorectal-type columnar mucosa proximally (dividing the upper from the lower anal canal).

Question 9

Describe the anatomic location of the anal verge.

Answer 9

The anal verge is located at the junction of nonkeratinized squamous epithelium of the anal canal and keratinized squamous epithelium (true epidermis) of perianal skin.

Question 10

Which site carries a better prognosis: the anal margin or anal canal?

Answer 10

The anal margin carries a better prognosis.

Question 11

Which pathology carries a higher risk for LR and distant recurrence?

Answer 11

Adenocarcinoma carries a higher risk.

Question 12

What is the significance of the dentate line in terms of LN drainage?

Answer 12

Above dentate line: drains to pudendal/hypogastric/obturator/hemorrhoidal → internal iliac nodes

Below dentate line: drains to inguinal/femoral nodes → external iliacs

Question 13

What % of anal cancer pts present with +LNs?

Answer 13

25%–35% of these pts present with +LNs.

Question 14

What are the 2 most common sites of DM?

Answer 14

Liver and lung

Question 15

What is the occult positivity rate for inguinal nodes (i.e., if clinically–) in anal cancer?

Answer 15

For inguinal nodes, the occult positivity rate is 10%–15%.

Question 16

What is the rate of extrapelvic visceral mets at presentation for anal cancer?

Answer 16

Extrapelvic visceral mets are present in 5%–10% of pts.

Question 17

In anal cancer, what % of clinically palpable LNs are actually involved by cancer?

Answer 17

50% of clinically palpable LNs involve cancer, while the other 50% are usually reactive hyperplasia.

Question 18

In anal cancers, what are the most important prognostic factors for LC and survival?

Answer 18

Tumor size and DOI predict for LC. The extent of inguinal or pelvic LN involvement predicts for survival.